Cardiovascular diseases remain the major cause of morbidity and mortality in United States. It is estimated that 12.4 million Americans have coronary artery disease and more than one million perople will develop a heart attack every year. The goal of this study is to induce myocardial regeneration of injured heart by trans-differentiation of cardiac fibroblasts into functional myocytes for replacing, repairing, maintaining, and enhancing the cardaic function. The hypothesis is that 5-aza-2'-deoxycytidine can induce myogenic trans-differentiation of cardiac fibroblasts to provide new muscle cells and improve ventricular function. The specific aims are 1). implant 5-aza-2'-deoxycytidine treated autologous cardiac fibroblasts into infarct heart for myocardial regeneration, 2). investigate the possible mechanisms of myocardial regeneration by implantation of trans-differentiated autologous cardiac fibroblasts. 5-Azacytidine has been used to produce functional muscle cells from non-muscle precursor cells such as fibroblasts, keratinocytes, mescenchymal stem cells, and bone marrow stromal cells. The formation of muscle cells from cardiac fibroblasts in culture after 5-aza-2'-deoxycytidine treatment has been observed by us. The changes in gene expression induced by the drug will be investigated by Western blot or 2-D electrophoresis (for proteins) and macroarrray or quantitative PCR (for mRNA). Reproducible infarction in canine myocardium produced by occlusion of left anterior descending coronary artery and vein will be used for the proposed study. Proteins specific to cardiac or skeletal muscel (TnI, myosin, connexin 43, myogenin) will be used to indicate the phenotypes of regenerated muscle by identifying the specific mRNA (Northern blot, RT-PCR) or proteins (Western blot, immunohistology). The global and regional (ischemic vs normal areas) functions will be determined before, during, and after coronary occlusion to assess the hemodynamic benefits of the treatment. The ratio of infarct or scar area to the ischemic area (risk zone) and pathologic evaluations will be performed on all of the control and treated animals. Expected beneficial outcomes will be reduced scar area due to induced myocardial regeneration, improved regional contractility, and prevented ventricular remodeling and failure. Success of this project may provide innovative approaches to treat myocardial infarction or cardio-myopathies associated with muscle cell loss and interstitial fibrosis.